Anti-streaking printing plate having inner edge spaced from supporting surface



Aprll 5, 1966 J. BRYER 3,244,098

ANTI-STREAKING PRINTING PLATE HAVING INNER EDGE SPACED SUP G SU GE Filed y 24, 1962 RFA FROM

INVENTOR.

UAcK BRYER HTTORNE rs United States Patent ANTI-STREAKING PRINTING PLATE HAVING INNER EDGE SPACED FROM SUPPORTING SURFACE Jack Bryer, Paramus, N.J., assignor to R. Hoe & Co., Inc., New York, N.Y., a corporation of New York Filed July 24, 1962, Ser. No. 212,096 4 Claims. (Cl. 101-375) This invention relates to a printing plate and plate mounting, minimizing streaking.

In relief printing, particularly at modern high speeds, the phenomenon known as streaking frequently occurs, the printed product showing streaks of heavy and light printing parallel to the cylinder axis. Such streaks commonly occur at regular intervals, tending to be most intense toward the leading edge of the plate and fading out or disappearing toward the trailing edge. While this diificulty has been associated with the impact of the impression blanket against the leading edge of the plate and following the passage of a gap between the ends of the blanket, it has heretofore been found impossible to deal with the difiiculty in a satisfactory manner or, indeed, to associate it in any demonstrable way with vibration of the machine elements.

It is the general object of the present invention to provide a plate construction and mounting of a streak minimizing character.

The invention provides in conjunction with a generally cylindrical plate and cylinder, a plate thickness variation of such character as not to interfere with the printing but to relieve impact or deaden transmission of shock waves due to impact with the leading edge of the plate.

Plate constructions embodying the invention will now be described with reference to the accompanying drawing, and the features forming the invention will then be pointed out in the appended claims.

In the drawing:

FIG. 1 is a somewhat schematic isometric of a plate embodying the invention in a preferred form;

FIG. 2 is a much enlarged fragmentary section of the plate of FIG. 1;

FIG. 3 is a sectional view showing the plate of FIGS. 1 and 2 mounted on a cylinder;

FIGS. 4 and 5 are enlarged sectional views showing a modification.

The plate, except as below mentioned, may be of any usual construction, and may be clamped to the cylinder by mechanism of any usual type such as the hook arrangement of Harless Patent No. 2,832,288.

FIG. 1 shows a stereotype printing plate 1 of otherwise usual construction, but from which metal adjacent the leading edge of the plate has been removed as at 2 to a depth of substantially .004 inch (the plate thickness being about inch, as usual), and over an arc of about 1 /2 inches in length (the total arcuate length of the plate from leading to trailing end being substantially 22 inches or thereabouts, as usual), as shown in FIG. 2. In the plate shown by way of example, the underside is formed with ribs 3 approximately M; of an inch deep so that the indicated relief at 2 cuts partway into these ribs. Pockets 4 cutting through the ribs and partly into the solid part of the plate are provided for engagement by the hooks 5 of thecylinder 6 at suitably spaced intervals along the plate edge.

It is found when the plate, thus relieved adjacent its straight ends, is clamped up (FIG. 3) and run on a cylindrical cylinder that previously noted objectionable streaking disappears.

An alternative structure is indicated in FIG. 4, in which an otherwise standard plate 1 (machined cylindrically on the inside and concentrically to the outside) is clamped up on a cylinder 6' in which a slight flat 7 is formed, to a radial depth of about .004 inch (under the leading edges of the plate and between the plate clamps or hooks 5), for obtaining the same relief as in the embodiment of FIG. 1 and also eliminating streaking. As shown in FIG. 4, the plate end before running may be somewhat spaced from the flat 7, but may be pressed down against the same in operation, as shown in FIG. 5.

While there is ordinarily no advantage in so doing, the relieved end of the plate may be blended gradually with the plate central thickness in the embodiment of FIG. 1 or the cylinder may be machined to an arc of larger radius than the cylinder instead of to a flat, where desired, so long as the essential feature of spacing the plate in its normal cylindrical condition slightly from the cylinder at its ends is maintained.

The relief of the plate end may be provided only at the leading end of the plate but is preferably provided at both ends so as to minimize jumping action by the form rollers.

What is claimed is:

1. In a relief printing machine, and in combination, a plate cylinder, a semi-cylindrical plate, cooperating plate clamping means on the cylinder and plate for holding the plate to the cylinder along a line parallel to and spaced from each straight edge of the plate, the plate and cylinder having cylindrical engaging surfaces extending from clamping means to clamping means, the plate having a concentric cylindrical outer surface extending around it from leading to trailing edge, and the inner surface of the plate adjacent a straight edge being spaced from the cylinder surface, such spacing continuing for a major part of the distance from the plate straight edge to the adjacent clamping means, whereby under printing pressure the plate edge is displaced radially inward, so as to provide a gradual increase of pressure on the plate as its edge passes the line of impression, thereby reducing streaking. 3

2. In a relief printing machine, the combination according to claim 1, in which the said spacing between the inner surface of the plate and the cylinder surface is about .004 inch, radially.

3. -In a relief printing machine, the combination according to claim 1, in which the cylinder has a flat under the leading edge of the plate, and the leading edge of the plate follows the cylindrical contour of the cylinder apart from the said flat, whereby a radial spacing of about .004 inch between plate edge and cylinder is obtained.

4. A semi-cylindrical printing plate having parallel cylindrical inner and outer surfaces, and recess means disposed parallel to its straight edges spaced therefrom, for engagement by cylinder clamping means to hold the plate on a cylinder, the outer plate surface being cylindrical substantially from straight edge to straight edge 3 thereof, and the inner surface being relieved adjacent one straight edge and backward toward the said recess means for the major part of the distance from the plate edge to the said recess means.

References Cited by the Examiner UNITED STATES PATENTS Tollison 101378 Crafts 101378 Chase et a1. 101378 Chase 101-378 Chase 101378 Crafts 101-378 ROBERT E. PULFREY, Primary Examiner.

EDGAR S. BURR, Assistant Examiner. 

1. IN A RELIEF PRINTING MACHINE, AND IN COMBINATION, A PLATE CYLINDER, A SEMI-CYLINDRICAL PLATE, COOPERATING PLATE CLAMPING MEANS ON THE CYLINDER AND PLATE FOR HOLDING THE PLATE TO THE CYLINDER AONG A LINE PARALLEL TO AND SPACED FROM EACH STRAIGHT EDGE OF THE PLATE, THE PLATE AND CYLINDER HAVING CYLINDRICAL ENGAGING SURFACES EXTENDING FROM CLAMPING MEANS TO CLAMPING MEANS, THE PLATE HAVING A CONCENTRIC CYLINDRICAL OUTER SURFACE EXTENDING AROUND IT FROM LEADING TO TRAILING EDGE, AND THE INNER SURFAFE OF THE PLATE ADJACENT A STRAIGHT EDGE BEING SPACED FROM THE CYLINDER SURFACE, SUCH SPACING CONTINUING FOR A MAJOR PART OF THE DISTANCE FROM THE PLATE STRAIGHT EDGE TO THE ADJACENT CLAMPING MEANS, WHEREBY UNDER PRINTING PRESSURE THE PLATE EDGE IS DISPLACED RADIALLY INWARD, SO AS TO PROVIDE A GRADUAL INCREASE OF PRESSURE ON THE PLATE AS ITS EDGE PASSES THE LINE OF IMPRESSION, THEREBY REDUCING STREAKING. 